Rotary electrical apparatus



Now ,13, 1945. w. B. WHELAN 2,388,889

I ROTARY ELECTRICAL APPARATUS Filed June 23, 11943 2 eets-Sheet 1 Ex; WZZZzZczm fi z/i m ATTORNEYS.

Nov. 13, 1945. w. B. WHELAN ROTARY ELECTRICAL APPARATUS Filed June 25, 1945 et -Sheet 2 ATTORNEYS.

=tion :therein, and one :the invention Patented Nov. 13, 1945 UNITED STATES. PATENT OFFICE 2,388,889 FRQTA'RY ELECTRICAL APPARATUS William B. "Whelan, Chicago, Ill. Applicationflunei23, 194 3, S'criaI'N0. 491;984 ,4 Claims. 1 Cl. 1,71- 228) :My invention relates to electrical apparatus, and more particularly to inhibiting sparking acof my objects is-to *provide :an improved arrangement 'of the *character =indicated which is of simple construction.

Another object of the invention is to provide means for the above "purpose which are highly :e'fiicient in -use.

.A "further object f the invention is 'to design for economical production. In the accompanying drawings:

:a longitudinal section and partial schematic view of an electrical generator --*or m'o tor -'embodying the invention and in which -cermagnets H, :coils 12, '(of which but one winding is illustrated diagrammatically) a commutator Brand :the shaft 1 4 typical of an ordinary two pole electrical generator. coils l2 are connected to i The ends l5 of the Fig. 1.

The brushes cooperating with the commutator l3 are made in three sections l6, l1, and I8 assembled asbest indicated in Fig. 2, with the those skilled in the art. It is to be noted from Fig. 2, wherein the brush assembly l6, I1, I8 is indicated as disposed obliquely, that the width angles and equally insulation. Accord- "in ly the three brushes 46, with their insulation spacing span :more than two commutator segments, so

I"! and I8 together 28 are designed to that during operation with the commutator turning counter-clockwise in Fig. 2 the vforemost brush 13 which likethetrailingbrush lG-is conof the squelch resistance 2| to H engages its segment, comnected by means the central brush municating 'a'reduced voltage with respect to the central segment I I. For this reason sparking 'upon-enga'gementof the forerunner brush I8 .is correspondingly diminished.

As a means for 1. The assembly 22 is surrounded and enclosed by a casing 23 which is fixed to the armature shaft I4 by bolts 22b or other suitable means,

and revolves therewith. The segments of the A circuit breaker 24 is provided for each segment of coils I2 as indicated in Fig. 1. Each circuit breaker 24 is carried by a cross head 26, and comprises a carbon electrode 24 electrically insulated from the main body of cross head 26 by spacers 21. Each cross head 26 carries a transverse guide bar 28 guide slots 29 in the sides of sponding coil l2, and interrupting the flow of current to the segment upon which the central brush [1 is momentarily entering into contact until said brush has substantially engaged the surface of said segment. The cams 3| are so positioned that at the time of the greatest tendency for sparking under the brushes l1, the coil connected with the external circuit is automatically short-circuited by the collector brushes. While the circuit is thus interruptedwith reference to a particular segment as it is approached by the brush H the adjacent circuits or those of the adjacent segments of commutator l3 continue nevertheless, since the switches 24 pertaining to their terminal wires 25 are not at that instant raised by the cams 3| so that excitement of their related coils, diminished by the resistance elements 2|, obtains during the instant that the particular segment is momentarily de-energized. Thus, sparking is greatly reduced or actually prevented. In this way an electrical apparatus employing brushes and a commutator, such as an electrical generator or motor, may be constructed in which the sparking under the brushes will be greatly minimized if not actually eliminated. lhe specific arrangement of parts disclosed is a simple and effective one for the purpose.

While I have described the invention along specific lines, various minor changes or refinements may be made therein without departing from its principle, andI desire to consider such changes and refinements as coming within the scope and spirit of the appended claims.

I claim:

7 1. In combination with a dynamo electric machine having an armature, coils, segmental commutator, and brushes, a rotary segmental assembly driven in synchronism with the commutator and corresponding in structure therewith, the rotary segmental assembly having its diametrically opposite segments electrically connected to each other, said assembly including a shiftable circuit breaker normally making electrical contact with each of said segments, the

diametrically opposite circuit breakers being connected in series with each coil, and means for successively shifting each circuit breaker to break each coil circuit as the brushes pass the corresponding commutator segments.

2. In an electric dynamo, a rotary armature having a plurality of windings, a segmental commutator having diametrically opposite segments thereof connected to each of said windings, a circuit breaker rotatable in synchronism with said commutator and comprising a circumferential series of segments insulated from each other, the diametrically opposite ones of said last segments being electrically connected, a contactelement normally engaging each of said last segments, diametrically opposed contact elements being connected to the respective windings to which the diametrically opposite commutator segments are connected, and means operative upon rotation of the circuit breaker for successively moving the contact elements out of engagement with the associated segments during a brief interval when the brushes are beginning to make contact with the segments connected to the respective windings.

3. The structure according to claim 2 wherein said circuit breaker comprises a frame rotatable with said series of segments, said contact elements being radially movable in said frame, spring means supported in the frame normally urging the contact elements into engagement with the respective segments, and fixed cam means disposed for successive engagement with the contact elements for moving same out of contact with the segments against the action of said spring means.

4. The structure according to claim 2, wherein each of said contact elements is carried by and insulated from a cross head, a spring normally urging each cross head radially inwardv for contact of the respective element with a' segment and cam means for moving the respective cross heads radially outward for breaking contact between the respective elements and segments.

WILLIAM B. WHELAN. 

